The present invention relates to a process for converting a continuous structure into discrete, spaced apart elements. Such a process is applicable in the industrial manufacture of discrete articles which are assembled from raw materials supplied in continuous form.
Generally, the industrial manufacture of discrete articles relies on the assembly of individual articles from continuously supplied raw materials. Continuously supplied raw materials can be supplied to the manufacturing process in a much more convenient way than discrete raw materials. The continuously supplied raw materials are cut to obtain discrete elements which are then deployed in the articles. Often, it is desirable to space apart the elements in the machine direction to improve the processability of the elements, e.g. in the context of enveloping or packaging.
In many cases, articles comprise fragile elements which are combined with, for example, a protective layer or a packaging layer. These additional layers can provide support to the fragile elements to avoid disintegration of the elements by external forces encountered during transport, storage, and use.
When the raw material for such fragile elements is supplied to the making process in form of a continuous structure, the conversion of the continuous structure into discrete, spaced apart elements such that they can subsequently be covered or wrapped requires a lot of effort and caution on the process side. In particular, spacing apart the fragile elements as such requires a pull force which is potentially harmful to the integrity of the discrete elements. Secondly, reducing the pull force for improved element handling requires the reduction of the line speed.
One example of discrete articles comprising fragile elements are disposable absorbent articles. Typically, an absorbent core comprised in such disposable absorbent articles is based at least partially on a cellulosic fibrous matrix wherein the integrity of the absorbent core often relies on the entanglement of the individual fibers. In addition, disposable absorbent articles generally comprise a topsheet and backsheet between which the absorbent core is sandwiched. By joining topsheet and backsheet at least along the periphery of the absorbent core, the disintegration of the fragile absorbent core is reduced. Some disposable absorbent articles even comprise additional wrapping layers around the absorbent core to further reduce disintegration of the absorbent core.
Specifically, U.S. Pat. No. 5,458,592 issued to Abuto et al. teaches an absorbent core completely wrapped in a thermoplastic fibrous nonwoven web. The process for making these absorbent structures as described in this patent is limited to the formation of discrete, spaced apart absorbent cores. This specific formation allows the subsequent wrapping of the cores without needing to space apart the fragile absorbent cores before wrapping them.
On the other hand, continuous absorbent core formation processes, as described for example in U.S. Pat. No. 4,904,440 issued to Angstadt, have the need that the continuous web of absorbent cores has to be cut into discrete cores and subsequently these discrete cores have to be spaced apart before they can be combined with another continuous web (such as a core wrap, topsheet, backsheet, or the like) at spaced apart positions. Especially in the context of fragile absorbent cores, these operations on the discrete absorbent cores cause line speed limitations, increased process complexity and maintenance effort.
Hence, it is an objective of the present invention to provide a process for converting a continuous structure into discrete, spaced apart elements without imposing the above limitations.
Therefore, the process of the present invention is particularly well suited for the manufacture of discrete articles comprising fragile absorbent cores.
It is an object of the present invention to provide a process for converting a continuous structure into discrete, spaced apart elements, comprising the steps of (a) supplying a continuous support web which is combined with the continuous structure, the support web comprising at least one longitudinal expansion means; (b) separating the continuous structure into discrete elements; and (c) longitudinally spacing apart the discrete elements by expanding the support web. Thereby, the support web preferably comprises at least one deactivatable expansion obstruction means. In a preferred embodiment of the process of the present invention, the step of deactivating the deactivatable expansion obstruction means of the support web is comprised in the process. Alternatively, the support web may be a discontinuously expanding web.
It is a further object of the present invention to provide a process which comprises a step of introducing designated transverse separation zones into the continuous structure.
It is a further object of the present invention to provide a process for converting a continuous structure into discrete, spaced apart elements wherein the step of expanding the support web is carried out by a series of two consecutive conveyors transporting the support web, the second conveyor having a higher transportation velocity than the first conveyor.
It is a further object of the present invention to provide a process for converting a continuous structure into discrete, spaced apart elements which comprises the step of forming the continuous structure of core elements and the step of transferring the continuous structure onto the support web.
It is a further object of the present invention to provide a process for converting a continuous structure into discrete, spaced apart elements which comprises the step of forming the continuous structure on the support web.
It is a further object of the present invention to provide a process for converting a continuous structure into discrete, spaced apart elements wherein the elements are absorbent cores.
It is a further object of the present invention to provide a process for making discrete articles comprising at least one discrete element and a support web, wherein the process comprising the steps of converting a continuous structure into discrete, spaced apart elements and the step of separating the continuous support web between at least some the discrete elements.
It is a further object of the present invention to provide a process for making discrete articles which comprises the step of folding the support web around at least one longitudinal or at least one transverse edge of the discrete elements.
It is a further object of the present invention to provide a process for making discrete articles further comprising the step of longitudinally wrapping the support web around the discrete elements such that the longitudinal edges of the support web overlap and the step of completely enveloping the discrete elements by sealing the support web along the overlapping longitudinal edges of the support web and by sealing the support web outside the transverse edges of the discrete elements.
It is a further object of the present invention to provide a process for making discrete articles which comprises the step of supplying a second support web and the step of positioning the discrete elements intermediate the support web and the second support web.
It is a further object of the present invention to provide a process for making discrete articles which comprises the step of completely enveloping the discrete elements by attaching the support web to the second support web outside the longitudinal and transverse edges of the discrete elements.
It is a further object of the present invention to provide a process for making discrete articles wherein the articles are absorbent articles.